Sound receiving apparatus



some]: RECEIVING APPARATUS Original Filed Oct. 51. 1929 1 fiverzZo-n May 29,1934

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PATET SOUND RECEIVING APPARATUS Ivan O. Clement, Greenwood, Mass, assignor to Submarine Signal Company, Boston, Mass, a

corporation oi Maine Claims. (01. 177-386) The present invention relates to subaqueous sound receiving devices, and more particularly to v such devices which are mounted in the skin of a vessel, which invention is a division of United 5 States application Serial No. 403,825, filed October '31, 1929.

To provide a good so-called skin mounted instrument there are usually two factors, among others, .which demand careful consideration. The device must be rugged; it must be possible to install it in a vessel and be certain that it will stand up under severe weather conditions without breaking down or leaking and produce good results for a long period of time without excessive tests, examinations or repairs. The device must also be free from acoustic vibrations.

In the present invention both ofthese aims are accomplished to a remarkable degree, due to the particular construction employed.

In the prior art, it has been common practice to use rubber insulation for acoustic damping, but such insulation has not always been used in the manner to accomplish the best possible acoustic damping. This is probably due to the fact that the sound device was clamped in such a manner that stresses were set up by bending which caused extraneous vibrations. Such extraneous vibrations may be set up where the clamping is accomplished through faste 1 at two points to so the ships skin. If the vibration of the structures at these two points is not in the same phase and does not possess substantially the same'amplitude, there are liable to be some extraneous vibrations present. In making the present invention, I discovered this dimculty and have made a construction in which this efiect is entirely remedied, at the same time acoustically insulating the entire sound receiving unit as a whole.

In'the structure employed in the present invention the inertia ring is directly and rigidly attached to the ship's skin. This inertia ring is made of such a concentrated mass with respect to the skin of the vessel surrounding it that the large amplitudes of vibration in the skin are substantlally converted into very small vibration in the ring. Further than this, the clamping of the sound receiver or its point of support is made at such a point remote from where the ring attaches to the skin and to the ring alone so that not only so the vibrations at the clamping point in the ring 1 may be a minimum but also so that as little sound conduction as possible transmitted through the skin mayaflect the receiver. The noise in the ship's skin affects the receiving unit in part at least by sound conduction and if the sldn'and the receiver are associated with the ring in the same vicinity or in the same line of ton, considerable of this energy will reach the receiver casing and affect the receiver.

This construction also provides excellent means for maintaining a watertight installation which remains watertight. 4

In the present construction, I also provide a special type of diaphragm, particularly adapted for skin mounted construction because of its mechanical and acoustic properties.

Further objects and aims of the present invention, as well as advantages over the prior art,'will be more fully understood from a consideration of the following description of the embodiment of the same in connection with the drawing showing a sectional view of the device.

g In the drawing, the ship's skin is represented as 1. A hole is cut in the skin in which is mounted the heavy ring 2 having as an integral portion a cylindrical neck 24 fitting within the edge of the hole. The ring 2 is riveted to the ship's skin or plate by the rivets 5 and is made tight by a gasket 20 or calking between the plating and the ring. To further secure the ring 2, it is welded at 4 to the ship's skin. The. ring 2 is formed with an inwardly extending flange 25, the purpose of which will be discussed more fully later.

The hydrophone unit 9 is inserted from the outside of the vessel and must, therefore, be installed when the ship is in dry dock. It is formed of a cylindrical shell 26 with an outwardly extending flange portion 21, the outer face 10 of which forms a continuous surface with the ship's skin and the hydrophone diaphragm 11. the rim of the outer-flange 21 is placed a sound insulating shell 3 and between the inner face of the flange 21 and the inwardly extending flange 25 is the insulating element 13, while between the cylindrical wall 26 and the flange 25 is the insulating element 1 4. These acoustic insulating elements are preferably one piece and are put over the shell of the hydrophone unit from the back end. In this mannerthey are securely and firmly held in position.

The shell 26 is threaded on the outer side at 27 to receive a threaded collar 8, which clamps the unit securely to the inwardly extending flange 25. Between the collar 8 and the flange 25 is the insulating ring 6 and the clamping ring 7.

About It, will be noted that the hydrophone unit is f clamped to the heavy ring 2 by straight pressure clamp ng and compression. or the flange of the ring itself without forces such as bending or torsion being present. The clamping is effected between parallel surfaces substantially in an align,- ment perpendicular to the diaphragm surface.

The end of the hydrophone unit is closed by suitable watertight mechanism through which the cable 28 is conducted to the microphone 1'7. The diaphragm 11 of the hydrophone is made of soft rubber and sets in a seat formed by the inwardly extending flange 29 and the shoulder 30. On the outside it is flush with the skin of the ship and is held in this position by being cemented to the metal and by the clamping pieces 16 and 31. The clamping element 16 rests against the narrow neck of the diaphragm and pressure is exerted upon itby the ring 31, threading in the inner side of the shell 26. The diaphragm 11 is formed with a heavy outer edge, a thinner neck 23 and a thick center portion. It may be molded and has set therein a ring insert 15, preferably made of some hard fibrous material. The. element 16 and the construction of theseat for the diaphragm are so formed that this insert takes up practically the entire neck area and therefore prevents any cold flow of rubber between the clamping surfaces. In this manner, the joint is maintained watertight and has no tendency to leak after a time. In addition, the insert strengthens the diaphragm and prevents certain detrimental frictional losses.

The microphone button 1,? is mounted on a stem 18 which is molded with a plate in the diaphp. '1

The whole structure is one, adaptable for a skin mounted installation and because of the con-' struction almost entirely eliminates transmission of ships sounds from the hull or skin-to the sound receiver.

This is in part accomplished, it is believed, be-

cause of the suspension of the unit entirely onthe heavy inertia ring and because of the mannor of clamping the unit to the ring.

Ha now described my invention, I claim: 1. In combination with a vessel having a hole in the skin thereof, a heavy inertia ring attached to the skin surrounding the hole and having an outwardly extending portion lining the hole edge of the plate and a portion projecting inward of said hole serving as a clamping plate, a sound receiving device having a casing and a. flange projecting at the side of the said casing, the in- '-:-.-=ii diameter of the outwardly extending portion the hole edge and the flange of the cg being such that these portions are spaced from each other, a ring and means for adjusting the position of the ring on the casing to form with the flange of said casing a clamping means and means interposed between the surfaces of the inwardly extending portion of said ring and said clamping means for acoustically insulating the sound receiver.

2. In combination with a vessel having a hole in the skin thereof, a heavy inertia ring attached to the surrounding the hole and having an inwardly projecting portion serving as a c plate, a and receiving device he ii: a

neonate ing and a flange projecting on the outer side of said inertia plate, the diameter of the flange of the casing and that of the open hole on the outer side of the plate being such that the periphery of the flange is spaced from the edge of the hole, a ring and means for adjusting the position of the ring on the casing to form with the flange of said casing a clamping means, and acoustic insulating means surrounding the inwardly projecting flange to insulate the receiver.

3. In combination with a vessel having a hole in the skin thereof, a heavy inertia ring attached to the skin surrounding the hole and having an outwardly extending portion lining the hole edge, means welding the adjacent external edges of the skin and the ring, said ring also having a portion extending inward of said hole serving as a clamping'plate, a sound receiving device having a casing fitting into said hole and having an outwardly extending flange positioned to oppose the inwardly extending portion on said ring, the internal diameter of the outwardly extending portion lining the hole edge and the flange of the casing being such that these portions are spaced from each other, means appliedto said case associated with the flange on the case for clamping the sameto said ring, and acoustic insulating means for insulating the case from said ring.

4. In combination with a vessel having a hole therein a sound receiver positioned therein, having a casing with an outer face forming a continuous surface with the skin of the vessel, said face having a diaphragm continuous with it and forming a part of it, and a. flanged portion at 1 the periphery of said face, a heavy ring surrounding the hole and having a portion overlapping the hole abutting the flanged portion of the receiver, sound insulating means positioned between the portion overlapping the hole and 115 the flanged portion of the receiver, and means applied to the receiver to hold said last portions firmly together, the periphery of the flanged portion of the receiver being such a size. with respect to the hole that it is-spaced away from the edge of the hole.

5. In combination with a vessel having a hole in the slim thereof, a heavy interia ring attached to the skin surrounding the hole, said ring extending inwardly of the hole behind the opening and forming a clamping portion, asound receivreceiver away from the skin of the vessel and sound insulating material positioned between the casing and the inertia ring.

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